Method for manufacturing head including light source unit for thermal assist

ABSTRACT

Provided is a method and apparatus to manufacture a thermally-assisted magnetic recording head in which a light source unit including a light source and a slider including an optical system are joined. The method comprises steps of: adhering by suction the light source unit with a back holding jig; bringing the light into contact with a slider back surface; applying a load to a load application surface of the light source unit by a loading means to bring a joining surface of the light source unit into conformity with the slider back surface; positioning the light source unit apart from the slider, and then aligning the light source with the optical system; bringing again the light source unit into contact with the slider; and applying a load again to the load application surface.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for manufacturing athermally-assisted magnetic recording head used for thermally-assistedmagnetic recording in which a portion to be written of a magneticrecording medium is heated and thus writing is performed to the portionwhere anisotropic magnetic field decreases. The present inventionespecially relates to a method for manufacturing a thermally-assistedmagnetic recording head constituted by joining a light source unit and aslider. The present invention further relates to an apparatus used forthe joining.

2. Description of the Related Art

With the explosion in the use of the Internet in these years, more datathan ever before is stored and used on computers such as servers andinformation processing terminals. This trend is expected to further growat an accelerated rate. Under these circumstances, demand for magneticrecording apparatuses such as magnetic disk apparatuses as mass storageis growing, and the demand for higher recording densities of themagnetic recording apparatuses is also escalating.

In the magnetic recording technology, it is necessary for magnetic headsto write smaller recording bits on magnetic recording media in order toachieve higher recording densities. In order to stably form smallerrecording bits, perpendicular magnetic recording technology has beencommercially implemented in which components of magnetizationperpendicular to the surface of a medium are used as recording bits. Inaddition, thermally-assisted magnetic recording technology that enablesthe use of magnetic recording media having higher thermal stability ofmagnetization is being actively developed.

In the thermally-assisted magnetic recording technology, a magneticrecording medium formed of a magnetic material with a large energy K_(U)is used so as to stabilize the magnetization, then anisotropic magneticfield of a portion of the medium, where data is to be written, isreduced by heating the portion; just after that, writing is performed byapplying write field to the heated portion. Actually, there has beengenerally used a method in which a magnetic recording medium isirradiated and thus heated with a light such as near-field light(NF-light). In this case, it is significantly important where and how alight source with a sufficiently high light output should be disposedinside a head in order to stably supply a light with a sufficiently highintensity at a desired position on the magnetic recording medium.

As for the setting of the light source, for example, U.S. Pat. No.7,538,978 B2 discloses a configuration in which a laser unit including alaser diode is mounted on the back surface of a slider, and US PatentPublication No. 2008/0056073 A1 discloses a configuration in which astructure of a laser diode element with a monolithically integratedreflection mirror is mounted on the back surface of a slider.

The present inventors propose a thermally-assisted magnetic recordinghead with a “composite slider structure” which is constituted by joininga light source unit provided with a light source to the end surface(back surface) of a slider provided with a write head element, the endsurface being opposite to the opposed-to-medium surface of the slider.The “composite slider structure” is disclosed in, for example, US PatentPublication No. 2008/043360 A1 and US Patent Publication No. 2009/052078A1. The advantages of the thermally-assisted magnetic recording headwith the “composite slider structure” are as follows:

a) The head has an affinity with the conventional manufacturing methodof thin-film magnetic heads because the opposed-to-medium surface andthe element-integration surface are perpendicular to each other in theslider.

b) The light source can avoid suffering mechanical shock directly duringoperation because the light source is provided far from theopposed-to-medium surface.

c) The light source such as a laser diode and the head elements can beevaluated independently of each other; thus the degradation ofmanufacturing yield for obtaining the whole head can be avoided;whereas, in the case that all the light source and head elements areprovided within the slider, the manufacturing yield rate for obtainingthe whole head is likely to decrease significantly due to themultiplication of the process yield for the light-source and the processyield for the head elements.

d) The head can be manufactured with reduced labor and at a low cost,because there is no need to provide the head with optical componentssuch as a lens or prism which are required to have much high accuracy,or with optical elements having a special structure for connectingoptical fibers or the like.

It is important to appropriately join a light source unit to a slider infabricating the thermally-assisted magnetic recording head having the“composite slider structure”. Specifically, it is essential to provide asufficiently strong junction, to provide a heat dissipation path for thelight source after the joining, and to ensure a sufficiently highaccuracy of joining position.

A sufficiently strong junction can be provided by using metal solder tojoin the light source unit and the slider. In this case, the lightsource unit and the slider sandwich the metal solder therebetween. Thisarrangement can provide a heat dissipation path along which heatradiated from the light source is transferred sequentially to the unitsubstrate, the metal solder, the slider substrate, and a magneticrecording medium during write operations of the head flying above themagnetic recording medium.

When metal solder is used for the joining, the layer of the metal solderneeds to be formed to an appropriate thickness, for example a thicknessin the range of approximately 0.05 to 2 μm (micrometers). If the solderis too thin, it is difficult to provide sufficient joining strength. Onthe other hand, if the solder is too thick, the distance between thelight source unit and the slider will be so large that light emittedfrom the light source significantly attenuates before reaching anoptical system in the slider, possibly resulting in a significantlyreduced light use efficiency of the head. In addition, solder can flowinto the space between the light source and the optical system.

When solder with such limitations of thickness is used to join the lightsource unit and the slider, it is important to provide extremely high“conformity” between the joining surfaces of the light source unit andthe slider. The term “conformity” as used here means the degree ofparallelism of a surface to a reference surface, or the degree to whicha surface conforms to a reference surface. Suppose that the joiningsurface of a light source unit that is 500 μm wide in the track widthdirection is to be joined to the joining surface of a slider that iswell wider than the joining surface of the light source unit. Ifalignment conducted before joining is completed with the joining surfaceof the light source unit being tilted at a small angle of 0.5° (degree)to the joining surface of the slider and then the solder is melted tocomplete the joining, one end of the joining surface of the light sourceunit will be at a distance of at least approximately 4.4 μm apart fromthe joining surface of the slider. Even if the solder is 2 μm thick, agap will be formed between the joining surfaces and the strength of thejoining can be unacceptably reduced. If the joining is weak, the lightsource unit can become detached from the slider during a subsequentprocess step such as a cleaning step, or during use of the head.

A sufficiently high accuracy of joining position between the lightsource unit and the slider can be achieved by active alignment. Here,the active alignment is a method in which a light source such as a laserdiode is actually put into operation and, while the light source and anoptical system such as a waveguide are moved relatively to each other,light emitted from the light source and incident on the light-receivingend of the optical system is monitored on the light-emitting end side ofthe optical system in real time until the light intensity in themonitoring location is maximized, then the maximum intensity position isset as the desired relative position of the light source with respect tothe optical system. The active alignment requires that electric power besupplied to the light source of the light source unit by pressing probesagainst electrodes for the light source while the light source unit isbeing moved above the slider. There is a method for meeting therequirement in which the light source is held with a clamp in such amanner that the surface of the light source unit on which the electrodesare formed is not covered with the clamp, and the clamp holding thelight source unit is moved above a stage on which the slider is placedto align the light source unit to the slider.

However, it is difficult to sufficiently increase the conformity betweenthe joining surfaces of the light source unit and the slider by thismethod of moving the light source. In fact, the surfaces of the unitsubstrate of the light source unit has errors in squareness in relationto each other due to working accuracy limitations. In addition, thesurfaces of the clamp that holds the light source unit also has errorsand the movement of clamp with respect to the stage also has an errordue to adjustment limitations. Therefore, even when the clamp is movedcloser to the stage to bring the light source unit into contact with theslider, it is significantly difficult to achieve high conformity betweenthe joining surfaces of the light source unit and the slider. If aconformity adjustment mechanism such as an air gimbal is provided in thestage in order to address the conformity problem, the mechanism willhave little effect in adjusting conformity because the size of theslider placed on the stage is very small. The mechanism also addscomplexity to the joining apparatus.

As will be appreciated from the foregoing, there is a long felt need fora method capable of achieving an extremely high “conformity” between thejoining surfaces of the light source unit and the slider in joiningbetween the light source unit and the slider after aligning the lightsource unit and the slider with each other by active alignment.

SUMMARY OF THE INVENTION

Some terms used in the specification will be defined before explainingthe present invention. In a layered structure or an element structureformed in the element-integration surface of a slider substrate or inthe source-installation surface of a unit substrate of the magneticrecording head according to the present invention, when viewed from astandard layer or element, a substrate side is defined as a “lower”side, and the opposite side as an “upper” side. Further, “X-, Y- andZ-axis directions” are indicated in some figures showing embodiments ofthe head according to the present invention as needed. Here, Z-axisdirection indicates above-described “up-and-low” direction, and +Z sidecorresponds to a trailing side and −Z side to a leading side. And Y-axisdirection indicates a track width direction, and X-axis directionindicates a height direction.

According to the present invention, provided is a method formanufacturing a thermally-assisted magnetic recording head in which alight source unit including a light source provided in a unit substrateand a slider including an optical system provided in a slider substrateare joined to each other. The manufacturing method comprises the stepsof:

adhering by suction a unit back surface of the unit substrate with aback holding jig including a suction means, the unit back surface beingopposite to a source-installation surface of the unit substrate;

moving the back holding jig close to the slider to bring the lightsource unit adhered to the back holding jig by suction into contact witha slider back surface of the slider, the slider back surface beingopposite to an opposed-to-medium surface of the slider and including alight-receiving end surface of the optical system;

applying a load to a load application surface of the unit substrate by aloading means to bring a joining surface of the light source unit intoconformity with the slider back surface of the slider at least in atrack width direction, the load application surface being opposite tothe joining surface that is to be joined to the slider;

stopping applying the load, moving the back holding jig away from theslider to position the light source unit at a distance from the slider,and then aligning a light-emitting center of the light source with thelight-receiving end surface of the optical system in directions in aplane of the slider back surface;

moving the back holding jig again close to the slider to bring the lightsource unit into contact with the slider back surface of the slider; and

applying a load again to the load application surface of the unitsubstrate by the loading means to bring the joining surface of the lightsource unit into conformity with the slider back surface of the slider.

In the manufacturing method, it is preferable that probes are broughtinto contact with electrodes for the light source provided in the lightsource unit, electric power is supplied to the light source to put thelight source in emitting operation, and then the light-emitting centerof the light source is aligned with the light-receiving end surface ofthe optical system so that a light from the light source enters theoptical system.

In the above-described manufacturing method, the “conformity” betweenthe joining surface of the light source unit and the slider back surfaceof the slider can be significantly increased while the light source unitand the slider can be aligned with each other by active alignment inwhich the light source is actually put in emitting operation.Accordingly, an adequately strong junction and an adequately highaccuracy of the joining position can be achieved in the joining betweenthe light source unit and the slider. Here, the active alignment is amethod in which a light source is actually put into operation and, whilethe light source and an optical system such as a waveguide are movedrelatively to each other, light emitted from the light source andincident on the light-receiving end of the optical system is monitoredon the light-emitting end side of the optical system in real time untilthe light intensity in the monitoring location is maximized, then themaximum intensity position is set as the desired relative position ofthe light source with respect to the optical system. Further, the term“conformity” as used here means the degree of parallelism of a surfaceto a reference surface, or the degree to which a surface conforms to areference surface.

Further, in the method for manufacturing the thermally-assisted magneticrecording head according to the present invention, it is preferable thata suction force of the suction means provided in the back holding jig,with which the light source unit is sucked, has a magnitude such that aposition or orientation of the light source unit is changed under apredetermined load applied. Furthermore, it is preferable that thesuction means included in the back holding jig is at least one suctionhole provided in the back holding jig, and the light source unit isadhered by suction to the back holding jig by activating an evacuatorconnected to one end of the at least one suction hole. Moreover, it ispreferable that the loading means is a jig having a spherical or convexportion which is to contact with the load application surface of theunit substrate.

Further, in the method for manufacturing the thermally-assisted magneticrecording head according to a preferred embodiment, the manufacturingmethod preferably further comprises the steps of: forming an adhesionmaterial layer previously on the joining surface of the light sourceunit or the slider back surface of the slider or on both of thesurfaces, and bringing the joining surface into conformity with theslider back surface with the adhesion material layer sandwichedtherebetween; irradiating the adhesion material layer with a light thatincludes a wavelength that passes through the unit substrate through theunit substrate to melt the adhesion material layer; and bonding thelight source unit and the slider. In this case, by forming the unitsubstrate of a semiconductor material such as Si, GaAs or SiC and byirradiating the adhesion material layer with Nd-YAG laser light throughthe unit substrate and thus melting the adhesion material layer, thelight source unit and the slider can be joined.

According to a preferred embodiment, a joining apparatus used forconducting the above-described manufacturing method is further provided,which comprises:

a fixture for supporting the slider;

a back holding jig comprising: a suction means for adhering the lightsource unit by suction; and a suction surface that is to contact withthe unit back surface of the unit substrate, the back holding jig beingcapable of moving to adjust relative position of the light source unitwith respect to the slider held in the fixture;

a loading means for applying a load to the load application surface ofthe unit substrate;

probes to be pressed against electrodes for the light source provided inthe light source unit, provided for supplying electric power to thelight source in order to align a light-emitting center of the lightsource with the light-receiving end surface of the optical system indirections in a plane of the slider back surface; and

a controller configured to control movement of the back holding jig,suction by the suction means, application of load by the loading means,movement of the probes, and power supply to the light source through theprobes, as appropriate.

In the joining apparatus according to a preferred embodiment, thejoining apparatus preferably further comprises a photodetector fordetecting a light that is emitted from the light source to whichelectric power is applied through the probes, propagated through theoptical system, and emitted from the opposed-to-medium surface of theslider when aligning the light-emitting center of the light source withthe light-receiving end surface of the optical system. Furthermore, itis preferable that the joining apparatus further comprises a lightsource for adhesion for irradiating an adhesion material layer with alight that includes a wavelength that passes through the unit substratethrough the unit substrate, in order to melt the adhesion material layerand thus to bond the light source unit and the slider after forming theadhesion material layer previously on the joining surface of the lightsource unit or the slider back surface of the slider or on both of thesurfaces and bringing the joining surface into conformity with theslider back surface with the adhesion material layer sandwichedtherebetween.

Further objects and advantages of the present invention will be apparentfrom the following description of preferred embodiments of the inventionas illustrated in the accompanying figures. In each figure, the sameelement as an element shown in other figure is indicated by the samereference numeral. Further, the ratio of dimensions within an elementand between elements becomes arbitrary for viewability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view illustrating one embodiment of athermally-assisted magnetic recording head manufactured by amanufacturing method according to the present invention;

FIG. 2 shows a cross-sectional view taken by plane A in FIG. 1,schematically illustrating the structures of the head element part ofthe slider, the laser diode of the light source unit, and theirvicinities in the thermally-assisted magnetic recording head;

FIG. 3 shows a perspective view schematically illustrating theconfiguration of the waveguide, the near-field light generator and themain magnetic pole;

FIG. 4 shows a perspective view schematically illustrating aconfiguration of a principal part in one embodiment of a joiningapparatus for joining the light source unit and the slider by the methodfor manufacturing the thermally-assisted magnetic recording headaccording to the present invention;

FIG. 5 shows a perspective view schematically illustrating a comparativeexample for comparison with the mechanism for holding the light sourceunit in the joining apparatus according to the present inventionillustrated in FIG. 4;

FIG. 6 shows a schematic view illustrating junction between the joiningsurface of a light source unit and the slider back surface of a sliderwhen the “conformity” between both surfaces is inadequate;

FIGS. 7 a 1 to 7 j show schematic views illustrating one embodiment ofthe method for manufacturing the thermally-assisted magnetic recordinghead in which a light source unit is joined to a slider according to thepresent invention;

FIG. 8 shows a perspective view schematically illustrating a structureof a major part in one embodiment of a magnetic recording apparatusaccording to the present invention; and

FIG. 9 shows a perspective view schematically illustrating a structureof a major part in one embodiment of an HGA according to the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a perspective view illustrating one embodiment of athermally-assisted magnetic recording head manufactured by amanufacturing method according to a preferred embodiment of the presentinvention.

As shown in FIG. 1, a thermally-assisted magnetic recording head 21 isfabricated by aligning and joining a light source unit 23, whichincludes a laser diode 40 as a light source for thermal assist, and aslider 22, which includes an optical system 31.

The slider 22 includes: a slider substrate 220 having an air bearingsurface (ABS) 2200 processed so as to provide an appropriate flyingheight; and a head element part 221 that includes an optical system 31and is formed on an element-integration surface 2202 that isperpendicular to and adjacent to the ABS 2200. While, the light sourceunit 23 includes: a unit substrate 230 having an joining surface 2300;and a laser diode 40 as a light source provided on a source-installationsurface 2302 that is perpendicular to and adjacent to the joiningsurface 2300.

These slider 22 and light source unit 23 are bonded to each other insuch a way that a slider back surface 2201 of the slider substrate 220on the side opposite to the ABS 2200 and a joining surface 2300 of theunit substrate 230 are opposed to each other and sandwich a solder layer58 as an adhesion material layer therebetween.

(Light Source Unit)

In the light source unit 23 as also shown in FIG. 1, the laser diode 40can be a semiconductor diode of edge-emitting type. The laser diode 40has a light-emission center 4000 from which laser light for thermalassist is emitted. The laser diode 40 is provided in thesource-installation surface 2302 of the unit substrate 230 in such a waythat the light-emission center 4000 is opposed to the light-receivingsurface 430 of the optical system 31. The laser diode 40 is preferablybonded to the unit substrate 230 with a p-electrode layer 40 i (FIG. 2)down (so that the p-electrode layer 40 i faces the source-installationsurface 2302). In edge-emitting laser diodes in general, an active layer(light-emission center) and its vicinity where most amount of heat isgenerated lie closer to the p-electrode. Therefore, by setting thep-electrode 40 i as a bottom, the active layer becomes closer to theunit substrate 230 and the unit substrate 230 can more effectivelyfunction as a heatsink of the light source. As a result, there can beprovided a heat dissipation path along which heat radiated from thelaser diode 40 is transferred sequentially to the unit substrate 230,the solder layer 58, the slider substrate 220, and a magnetic recordingmedium during write operations of the head 21.

In this case of setting the laser diode 40 with the p-electrode 40 i asa bottom, the upper surface of the laser diode 40 is a surface of ann-electrode 40 a (FIG. 2). The n-electrode 40 a is an electrode withwhich a probe 67 is brought into contact in active alignment explainedin detail later with reference to FIG. 7 g.

Referring again to FIG. 1, a light source electrode 410 and a leadelectrode 411 are provided in a source-installation surface 2302 of thelight source unit 23. The light source electrode 410 is to be directlyelectrically connected to a p-electrode 40 i (FIG. 2) of the laser diode40. The lead electrode 411 is led from the light source electrode 410. Aprobe 67 will also be placed in contact with the lead electrode 411during active alignment, which will be described later in detail withreference to FIG. 7 g. The lead electrode 411 and an n-electrode 40 a ofthe laser diode 40 will be electrically connected to connection pads ofa wiring member 203 of a head gimbal assembly (HGA) 17 (FIG. 9) by amethod such as wire bonding or solder ball bonding (SBB) after the lightsource unit 23 is joined to the slider 22. The electrical connectionsenable power supply to the laser diode 40.

Preferably, an insulation layer 56 of an insulating material such asAl₂O₃ (alumina) or SiO₂ is provided on the source-installation surface2302, and on the insulation layer 56, the light source electrode 410 andthe lead electrode 411 are provided, thereby electrically insulating thelight source electrode 410 and the lead electrode 411 from the unitsubstrate 230. The light source electrode 410 and the lead electrode 411may include a foundation layer made of a material such as Ta or Ti andhaving a thickness of approximately 10 nm (nanometers), for example, anda conductor layer of a conductive material such as Au, Cu or an Au alloyformed on the foundation layer with a thickness in the range ofapproximately 1 to 5 μm (micrometers), for example.

Referring also to FIG. 1, the unit substrate 230 is preferably made of aceramic material such as AlTiC (Al₂O₃—TiC) or SiO₂ or made of asemiconductor material such as Si, GaAs or SiC. In the case that theunit substrate 230 is made of such a semiconductor material, the solderlayer 58 can be melted by irradiation with light such as Nd-YAG laserlight propagating through the unit substrate 230, thereby bonding thelight source unit 23 and the slider 22.

Further, the unit substrate 230 is somewhat smaller than the slidersubstrate 220. However, the width W of the unit substrate 230 in thetrack width direction (Y-axis direction) is larger than the width W_(LA)of the laser diode 40 in the track width direction (Y-axis direction),so that the lead electrode 411 is exposed in the source-installationsurface 2302 even after the laser diode 40 is mounted on thelight-source electrode 410. In the case of using a Femto slider as theslider substrate 220, for example, the unit substrate 230 may have athickness T_(UN) (in X-axis direction) of 350 μm, a width W_(UN) in thetrack width direction of 500 μm, and a length L_(UN) (in Z-axisdirection) of 300 μm.

The surface 2303 of the unit substrate 230 that is opposite to thesource-installation surface 2302 is to be brought into contact with asuction surface 620 of a back holding jig 62 that holds the light sourceunit 23, and to be adhered by suction to the suction surface 620, aswill be described later in detail with reference to FIG. 7 a 2. Thesurface 2303 will be hereinafter referred to as unit back surface 2303.The surface 2301 of the unit substrate 230 that is opposite to thejoining surface 2300 is a surface against which a round-tipped rod 65 isto be pressed in order to apply a load to the light source unit 23 toincrease the “conformity” of the joining surface 2300, as will bedetailed later with reference to FIG. 7 d. The surface 2301 will behereinafter referred to as load application surface 2301. The term“conformity” as used herein means the degree of parallelism of a surfaceto a reference surface, or the degree to which a surface conforms to areference surface.

(Slider)

In the slider 22 as also shown in FIG. 1, the head element part 221formed on the element-integration surface 2202 includes: a head element32 constituted of a magnetoresistive (MR) element 33 for reading datafrom the magnetic disk 10 (FIG. 8) and an electromagnetic transducer 34for writing data to the magnetic disk 10; a spot-size converter 43 thatreceives a laser light emitted from the laser diode 40, changes(reduces) the spot size of the laser light, then guides the laser lightinto the waveguide 35; a waveguide 35 that guides the laser light withchanged spot size to the head end surface 2210 as an opposed-to-mediumsurface or its vicinity; a near-field light (NF-light) generator 36 thatgenerates NF-light for thermal assist by coupling with the laser lightpropagating the waveguide 35; and an overcoat layer 38 formed on theelement-integration surface 2202 so as to cover the head element 32, thespot-size converter 43, the waveguide 35 and the NF-light generator 36.Here, the spot-size converter 43, the waveguide 35 and the NF-lightgenerator 36 constitute the optical system 31 for generating NF-light inthe head 21 (head element part 221). The spot-size converter 43 andwaveguide 35 are covered with the overcoat layer 38, and functions as acore in light propagation, whereas the portion of overcoat layer 38 thatcovers them functions as a clad.

One ends of the MR element 33, the electromagnetic transducer 34 and theNF-light generator 36 reach the head end surface 2210 as anopposed-to-medium surface. Here, the head end surface 2210 and the ABS2200 constitute the whole opposed-to-medium surface of thethermally-assisted magnetic recording head 21. During actual write andread operations, the thermally-assisted magnetic recording head 21aerodynamically flies above the surface of the rotating magnetic disk 10with a predetermined flying height. Thus, the ends of the MR element 33and electromagnetic transducer 34 face the surface of the magneticrecord layer of the magnetic disk 10 with a appropriate magneticspacing. Then, MR element 33 reads data by sensing signal magnetic fieldfrom the magnetic record layer, and the electromagnetic transducer 34writes data by applying signal magnetic field to the magnetic recordlayer. When writing data, laser light, which is generated from the laserdiode 40 of the light source unit 23 and propagates through thespot-size converter 43 and the waveguide 35, is changed into NF-light NF(FIG. 3) in the NF-light generator 36. Then, a portion to be written ofthe magnetic recording layer is irradiated and thus heated with theNF-light 62. As a result, the anisotropic magnetic field (coerciveforce) of the portion is decreased to a value that enables writing; thusthe thermally-assisted magnetic recording can be achieved by applyingwrite field WF (FIG. 3) with use of the electromagnetic transducer 34 tothe anisotropic-field-decreased portion.

Referring also to FIG. 1, the spot-size converter 43 is an opticalelement which receives laser light emitted from the laser diode 40 atits light-receiving end surface 430 having a width W_(SC) in the trackwidth direction (Y-axis direction), converts the laser light to laserlight having a smaller spot diameter with a lower loss, and then guidesthe converted laser light to a light-receiving end surface 352 of thewaveguide 35. The spot-size converter 43 in the present embodimentincludes a lower propagation layer and an upper propagation layer. Thelower propagation layer has a width in the track width direction (Y-axisdirection) that gradually decreases from the width W_(SC) along thetraveling direction (—X direction) of laser light incident through thelight-receiving end surface 430. The upper propagation layer has a widthin the track width direction (Y-axis direction) that more steeplydecreases from the width W_(SC) along the traveling direction (—Xdirection) of laser light than the lower propagation layer 431. Laserlight incident through the light-receiving end surface 430 is convertedto laser light with a smaller spot size as the laser light propagatesthrough the layered structure, and reaches the light-receiving endsurface 352 of the waveguide 35.

The width W_(SC) of the spot-size converter 43 at the light-receivingend surface 430 may be in the range of approximately 1 to 10 μm, forexample. The spot-size converter 43 is made of a material with arefractive index higher than the refractive index n_(OC) of theconstituent material of the surrounding overcoat layer 38. The spot-sizeconverter 43 can be formed from the same dielectric material as thewaveguide 35, which will be described below. In the case, the spot-sizeconverter 43 and the waveguide 35 may be formed integrally.

The waveguide 35 in the present embodiment extends in parallel with theelement-integration surface 2202 from the light-receiving end surface352 that receives laser light emitted from the spot-size converter 43 tothe end surface 350 on the head end surface 2210 side. Here, the endsurface 350 may be a portion of the head end surface 2210, or may berecessed from the head end surface 2210 with a predetermined distance. Aportion of one side surface of the waveguide 35 near the end surface 350faces a NF-light generator 36. This allows laser light (waveguide light)incident through the light-receiving end surface 352 and travelingthrough the waveguide 35 to reach the portion facing the NF-lightgenerator 36, thereby to be coupled with the generator 36.

Referring again to FIG. 1, a pair of terminal electrodes 370 and a pairof terminal electrodes 371 for the magnetic head element 32 are providedon the upper surface of the overcoat layer 38 of the slider 22. Theterminal electrodes 370 and 371 are electrically connected to connectionpads of wiring members provided in an HGA 17 (FIG. 9) by wire bondingmethod or SBB method. A mode of the connection between these terminalelectrodes and the wiring members on the flexure 201 will also bedescribed later in detail.

The slider substrate 220 may be, for example, a so-called Femto sliderhaving a thickness (in X-axis direction) T_(SL) of 230 μm, a widthW_(SL) of 700 μm in the track width direction (Y-axis direction), and alength L_(SL) (in Z-axis direction) of 850 μm. The Femto slider isgenerally used as a substrate for thin-film magnetic heads capable ofhigh-density recording, and has the smallest standardized size of allthe sliders currently on the market. The slider substrate 220 can beformed of a ceramic material such as AlTiC (Al₂O₃—TiC) or SiO₂.

(Thermally-Assisted Magnetic Recording Head)

As described above, the thermally-assisted magnetic recording head 21has a “composite slider structure” in which the slider 22 and the lightsource unit 23 are bonded to be joined. Thus, the slider 22 and thelight source unit 23 can be separately fabricated and then joinedtogether to fabricate the head 21. Consequently, if performance andreliability evaluations of the light source units 23 and the sliders 22are performed prior to the fabrication of the heads and only good lightsource units 23 and good sliders 22 are used for the fabrication of theheads, significantly adverse influence to the production yield of heads21 in the head manufacturing process due to the rejection rates oflight-source units 23 and sliders 22 can be avoided.

In fabricating the thermally-assisted magnetic recording head with the“composite slider structure”, it is significantly important toappropriately join the light source unit 23 and the slider 22.Specifically, it is essential to provide a sufficiently strong junction,to ensure a sufficiently high accuracy of joining position, and toprovide a heat dissipation path for the laser diode 40 after thejoining. There will be explained later, with reference to FIGS. 7 a 1 to7 j, a method for manufacturing the thermally-assisted magneticrecording head 21 according to the present invention, which meets theabove-described requirements.

FIG. 2 shows a cross-sectional view taken by plane A in FIG. 1,schematically illustrating the structures of the head element part 221of the slider 22, the laser diode 40 of the light source unit 23, andtheir vicinities in the thermally-assisted magnetic recording head 21.

(Laser Diode)

According to FIG. 2, the laser diode 40 is of edge-emitting type. As thelaser diode 40, InP base, GaAs base or GaN base diodes can be utilized,which are usually used for communication, optical disk storage, ormaterial analysis. The wavelength λ_(L) of the emitted laser light maybe, for example, in the range of approximately 375 nm to 1.7 μm. Thelaser diode 40 shown in FIG. 2 has a multilayered structure in which,from the upper surface side, sequentially stacked is: an n-electrode 40a; an n-GaAs substrate 40 b; an n-InGaAIP clad layer 40 c; the firstInGaAlP guide layer 40 d; an active layer 40 e formed of multiquantumwell (InGaP/InGaAlP) or the like; the second InGaAlP guide layer 40 f;an p-InGaAIP clad layer 40 g; a p-electrode base layer 40 h; and ap-electrode 40 i. Further, on the front and rear cleaved surfaces of themultilayered structure of the laser diode 40, respectively formed arereflective layers 510 and 511 for exciting the oscillation by totalreflection. Here, the light-emission center 4000 exists at the positionof the active layer 40 e on the reflective layer 510. In the presentembodiment, the n-electrode 40 a can be a layer made of, for example, Auor Au alloy with a thickness of approximately 0.1 μm and formed on then-GaAs substrate 40 b.

Of course, the structure of the laser diode 40 is not limited to theabove-described one. However, the laser diode 40 is preferably disposedin such a manner that the p-electrode 40 i is positioned at the bottomand is bonded to the light-source electrode 410. In edge-emitting laserdiodes in general, the active layer 40 e (light-emission center 4000) iscloser to the p-electrode 40 i than the n-electrode 40 a in thedirection in which the layers are stacked (in Z-axis direction).Accordingly, by setting the laser diode 40 with its p-electrode 40 i asa bottom, the p-electrode 40 i being closer to the active layer 40 ethat generates most amount of heat during operation, the unit substrate230 can more effectively function as a heatsink of the light source. Infact, the appropriate disposal of heat generated from the laser diode 40is very important for maintaining the oscillation operations of thelaser diode 40 in good working order.

Further, an electric source provided within the magnetic disk apparatuscan be used for driving the laser diode 40. In fact, the magnetic diskdrive apparatus usually has an electric source with applying voltage of,for example, approximately 2 to 5V, which is sufficient for the laseroscillation. The laser diode 40 may have a width W_(LA) (FIG. 1) in thetrack width direction (in Y-axis direction) lager than the width W_(UN)of the unit substrate 230. The length L_(LA) of the laser diode 40corresponds approximately to a cavity length that is the distancebetween the reflective layers 510 and 511, and is preferably 300 μm ormore in order to obtain a sufficient high output. Further, thep-electrode 40 i of the laser diode 40 and the light-source electrode410 of the unit substrate 230 can be bonded to each other by solderingusing a solder such as Au—Sn alloy.

(Head Element Part)

As shown also in FIG. 2, the head element part 221 includes an MRelement 33 and an electromagnetic transducer 34 and an optical system31.

The MR element 33 is formed on a base layer 380 that is formed of aninsulating material such as Al₂O₃ (alumina), SiO₂ and stacked on theelement-integration surface 2202. The MR element 33 includes: an MRmultilayer 332; and a lower shield layer 330 and an upper shield layer334 which are formed of a soft-magnetic material and sandwich the MRmultilayer 332 and an insulating layer 381 therebetween. The MRmultilayer 332 is a magneto-sensitive part for detecting signal magneticfield by utilizing MR effect. The MR multilayer 332 may be, for example:a current-in-plane giant magnetoresistive (CIP-GMR) multilayer thatutilizes CIP-GMR effect; a current-perpendicular-to-plane giantmagnetoresistive (CPP-GMR) multilayer that utilizes CPP-GMR effect; or atunnel magnetoresistive (TMR) multilayer that utilizes TMR effect.

The electromagnetic transducer 34 is designed for perpendicular magneticrecording, and includes an upper yoke layer 340, a main magnetic pole3400, a write coil layer 343, a coil-insulating layer 344, a lower yokelayer 345, and a lower shield 3450.

The upper yoke layer 340 is formed so as to cover the coil-insulatinglayer 344, and the main magnetic pole 3400 is formed on an insulatinglayer 385 made of an insulating material such as Al₂O₃ (alumina). Theseupper yoke layer 340 and main magnetic pole 3400 are magneticallyconnected with each other, and acts as a magnetic path for convergingand guiding magnetic flux toward the magnetic recording layer(perpendicular magnetization layer) of the magnetic disk 10 (FIG. 8),the magnetic flux being excited by write current flowing through thewrite coil layer 343. The main magnetic pole 3400 has an end surface3400 e with a small width W_(p) (FIG. 3) in the track width direction,the end surface 3400 e reaching the head end surface 2210. The widthW_(P) defines the width of distribution of write field WF in the trackwidth direction (Y-axis direction), and can be set to be, for example,0.05 to 0.5 μm. The main magnetic pole 3400 is preferably formed of asoft-magnetic material with a saturation magnetic flux density higherthan that of the upper yoke layer 340, which is, for example, an ironalloy containing Fe as a main component.

The write coil layer 343 is formed on an insulating layer 385 made of aninsulating material such as Al₂O₃ (alumina), in such a way as to passthrough in one turn at least between the lower yoke layer 345 and theupper yoke layer 340, and has a spiral structure with a back contactportion 3402 as a center. The write coil layer 343 is formed of aconductive material such as Cu (copper). The write coil layer 343 iscovered with a coil-insulating layer 344 that is formed of an insulatingmaterial such as a heat-cured photoresist and electrically isolates thewrite coil layer 343 from the upper yoke layer 340. The write coil layer343 has a monolayer structure in the present embodiment; however, mayhave a two or more layered structure or a helical coil shape. Further,the number of turns of the write coil layer 343 is not limited to thatshown in FIG. 2, and may be, for example, in the range from two toseven.

The back contact portion 3402 has a through-hole extending in X-axisdirection, and the waveguide 35 and insulating layers that covers thewaveguide 35 pass through the through-hole. In the through-hole, thewaveguide 35 is away at a predetermined distance of, for example, atleast 1 μm from the inner wall of the back contact portion 3402. Thedistance prevents the absorption of the waveguide light by the backcontact portion 3402.

The lower yoke layer 345 is formed on an insulating layer 383 made of aninsulating material such as Al₂O₃ (alumina), and acts as a magnetic pathfor the magnetic flux returning from a soft-magnetic under layer that isprovided under the magnetic recording layer (perpendicular magnetizationlayer) of the magnetic disk 10. The lower yoke layer 345 is formed of asoft-magnetic material. Further, the lower shield 3450 is a part of themagnetic path, being connected with the lower yoke layer 345 andreaching the head end surface 2210. The lower shield 3450 is opposed tothe main magnetic pole 3400 through the NF-light generator 36, and actsfor receiving the magnetic flux spreading from the main magnetic pole3400. The lower shield 3450 is preferably formed of a material with highsaturation magnetic flux density such as NiFe (Permalloy) or an ironalloy as the main magnetic pole 3400 is formed of. Here, the insulatinglayers 381, 382, 383, 384, 385 and 386 constitute the overcoat layer 38.

Referring also to FIG. 2, the optical system 31 includes a spot-sizeconverter 43, a waveguide 35 and a NF-light generator 36.

Laser light 53, the spot size of which the spot-size converter 43changes (reduces), enters the waveguide 35 from the light-receiving endsurface 352, and propagates through the waveguide 35. The waveguide 35extends from the light-receiving end surface 352 to the end surface 350on the head end surface 2210 side through the through-hole that isprovided in the back contact portion 3402 and extends in X-axisdirection. Furthermore, the NF-light generator 36 is an element thattransforms the laser light (waveguide light) 53 propagating through thewaveguide 35 into NF-light. A part on the head end surface 2210 side ofthe waveguide 35 and the NF-light generator 36 are provided between thelower shield 3450 (lower yoke layer 345) and the main magnetic pole 3400(upper yoke layer 340). Further explanation for the above-describedoptical system 31 will follow with reference to FIG. 3.

FIG. 3 shows a perspective view schematically illustrating theconfiguration of the waveguide 35, the NF-light generator 36 and themain magnetic pole 3400. In the figure, the head end surface 2210 ispositioned at the left side, the surface 2210 including positions wherewrite field and NF-light are emitted toward the magnetic recordingmedium.

As shown in FIG. 3, the configuration includes the waveguide 35 forpropagating laser light (waveguide light) 53 used for generatingNF-light toward the end surface 350, and the NF-light generator 36 thatreceives the waveguide light 53 and generates NF-light NF. Further, abuffering portion 50 is a portion sandwiched between a portion of theside surface 354 of the waveguide 35 and a portion of the lower surface362 of the NF-light generator 36. The buffering portion 50 is formed of,for example, a dielectric material that has a refractive index lowerthan that of the waveguide 35, and acts for coupling the waveguide light53 with the Nf-light generator 36. In the light source and opticalsystem as shown in FIGS. 1 to 3, the laser light emitted from thelight-emission surface 400 of the laser diode 40 preferably has TM-modepolarization in which the oscillation direction of electric field of thelaser light is along Z-axis.

Further, as also shown in FIG. 3, the NF-light generator 36 is, in thepresent embodiment, formed of a metal such as Au, Ag, or an alloyincluding Au or Ag, and has a cross-section taken by YZ-plane with atriangular shape. The end surface 36 a, which reaches the head endsurface 2210, especially has an isosceles triangle shape that has oneapex on the leading side (−Z side) opposed to the bottom edge. TheNF-light generator 36 converts the waveguide light 53 propagatingthrough the waveguide 35 into NF-light, and emits NF-light NF from theend surface 36 a. The NF-light NF is emitted toward the magneticrecording layer of the magnetic disk 10 (FIG. 8), and reaches thesurface of the magnetic disk 10 to heat a portion of the magneticrecording layer of the disk 10. This heating reduces the anisotropicmagnetic field (coercive force) of the portion to a value with whichwrite operation can be performed. Immediately after the heating, writefield WF generated from the main magnetic pole 3400 is applied to theportion to perform write operation. Thus, the thermally-assistedmagnetic recording can be accomplished.

The optical system that is provided in the head element part 221 andgenerates light for thermal assist is not limited to the above-describedone. For example, as an alternative, there can be available an opticalsystem that use a NF-light generator having another shape and structure,or an optical system in which a plasmon antenna made of a metal piece isprovided at the end of a waveguide.

FIG. 4 shows a perspective view schematically illustrating aconfiguration of a principal part in one embodiment of a joiningapparatus for joining the light source unit 23 and the slider 22 by themethod for manufacturing the thermally-assisted magnetic recording headaccording to the present invention.

Referring to FIG. 4, a joining apparatus 60 for joining the light sourceunit 23 to the slider 22 includes: a stage 61 which is a fixture forsupporting the slider 22; a back holding jig 62 having at least onesuction hole 630 which is suction means for attracting the light sourceunit 23 by suction; a round-tipped rod 65 which is loading means forapplying a load to the load application surface 2301 of the unitsubstrate 230; and probes 67 which are to be pressed against electrodesfor the laser diode 40 provided in the light source unit 23 to supplyelectric power to the laser diode 40.

The joining apparatus 60 further includes a controller 69. Thecontroller 69 controls the movement of the back holding jig 62 through aback-holding-jig drive unit 64, controls suction by the suction hole 630through an evacuator 63, controls application of load by theround-tipped rod 65 through a loading unit 660 and a load cell 661,controls movement of the probes 67 through a probe drive unit 681, andcontrols power supply to the laser diode 40 through an active-alignmentpower supply 680 and the probes 67, as appropriate. The controller 69may be a computer including software and a recording medium forappropriately providing the controls described above.

The back holding jig 62 includes a suction surface 620 which contactsthe unit back surface 2303 of the unit substrate 230. The suction hole630 passes through the back holding jig 62. One end of the suction hole630 reaches the suction surface 620, and the other end connects to theevacuator 63. Since the back holding jig 62 covers only the unit backsurface 2303 of the light source unit 23, the light source unit 23attached to the back holding jig 62 can be readily accessed externallyby various jigs and devices. The back holding jig 62 is connected to theback-holding-jig drive unit 64 and can be moved to adjust the relativeposition of the light source unit 23 with respect to the slider 22 heldon the stage 61.

Referring to FIG. 4, the round-tipped rod 65 has a spherical or convextip which presses and applies load to the light source unit 23. Theround-tipped rod 65 is connected to the loading unit 660 and the loadcell 661 which is a weight sensor. The round-tipped rod 65 applies apredetermined load to the load application surface 2301 of the unitsubstrate 230. The load application surface 2301 is the upper surface ofthe unit substrate 230 that is opposite to the joining surface 2300. Theround-tipped rod 65 may be replaced with alternative loading means suchas a rod having a minute tip surface such as a frustum of a triangularpyramid, a frustum of a quadrangular pyramid or a frustum of a cone.

The probes 67 are metal needles used for performing active alignment.The probes 67 are electrically connected to the active-alignment powersupply 680. One of the probes 67 in the present embodiment is pressedagainst a lead electrode 411 provided on the source-installation surface2302 of the light source unit 23 and the other to an n-electrode 40 a,which is the upper surface of the laser diode 40, to supply electricpower to the laser diode 40. In the active alignment, the light-emittingcenter 4000 of the laser diode 40 and the light-receiving end surface430 of the optical system 31 are aligned with each other in directionsin the plane of the slider back surface 2201 (directions in YZ-plane).Therefore, the probes 67, which are connected to the probe drive unit681, are movable so that the probe 67 on the electrode of the laserdiode 40 can remain pressed against the electrode during the alignment.

FIG. 5 shows a perspective view schematically illustrating a comparativeexample for comparison with the mechanism for holding the light sourceunit 23 in the joining apparatus 60 according to the present inventionillustrated in FIG. 4. FIG. 6 shows a schematic view illustratingjunction between the joining surface 2300 of a light source unit 23 andthe slider back surface 2201 of a slider 22 when the “conformity”between both surfaces is inadequate. The term “conformity” as used heremeans the degree of parallelism of a surface to a reference surface, orthe degree to which a surface conforms to a reference surface.

Referring to FIG. 5, a clamp 70 holds the light source unit 23 in thecomparative example. Specifically, two arms 700 and 701 of the clamp 70sandwich the light source unit 23 in such a manner that the arms 700 and701 are in contact with two side surfaces 2304 and 2305 of the lightsource unit 23 that are opposite to each other in the track widthdirection (in Y-axis direction). Accordingly, the light source unit 23is unable to rotate about Z-axis with respect to the clamp 70. Thesurfaces of the unit substrate 230 of the light source unit 23 haveerrors in squareness to each other due to working accuracy limitations.The surfaces of the arms 700 and 701 of the clamp 70 that sandwich thelight source unit 23 also have errors in squareness to each other.Movement of the clamp 70 with respect to the stage 71 also has an errordue to adjustment limitations. It will be understood from the foregoingthat it is difficult to maintain a high conformity between the joiningsurface 2300 of the light source unit 23 and the slider back surface2201 of the slider 22 even if errors in position and orientation of theclamp 70 with respect to the stage 71 are minimized and then the clamp70 is brought close to the stage 71 to bring the light source unit 23into contact with the slider 22.

Junction between the joining surface 2300 of the light source unit 23and the slider back surface 2201 of the slider 22 when the conformitybetween the joining surface 2300 and the slider back surface 2201 isinadequate will be described with reference to FIG. 6.

Suppose that the light source unit 23 (unit substrate 230) having awidth W_(UN) in the track width direction (in Y-axis direction) of 500μm is joined to the slider 22 as illustrated in FIG. 6. It is assumedhere that a solder layer 58 has been provided on the slider back surface2201 of the slider 22 and the thickness d_(ER) of the solder layer 58 is2 μm. It is undesirable to have the thickness d_(ER) of the solder layer58 too large, for example greater than 2 μm. If the solder layer 58 istoo thick, the distance between the light source unit 23 and the slider22 will be so large that light emitted from the laser diode 40 cansignificantly attenuate before reaching an optical system in the slider22, resulting in a significantly reduced light use efficiency of thehead. In addition, the solder layer 58 can undesirably flow into thespace between the laser diode 40 and the optical system.

If alignment between the joining surface 2300 of the light source unit23 and the slider back surface 2201 of the slider 22 is completed withthe joining surface 2300 of the light source unit 23 being tilted at asmall angle θ_(ER) of 0.5° (degrees) to the slider back surface 2201 ofthe slider 22 before joining and then the solder is melted to completethe joining, one end 2300 a of the joining surface 2300 of the lightsource unit 23 is adhered to the slider back surface 2201 by the solderlayer 58 whereas the other end 2300 b is a distance d_(ER) of 4.4 μMfurther apart from the slider back surface 2201 in +X direction ascompared with the end 2300 a. Even if the solder layer 58 is 2 μm thick,a gap is formed between a region of the joining surface 2300 near theend 2300 b and the slider back surface 2201 due to the tilt at an angleθ_(ER) of as small as 0.5°. As a result, the strength of the joining canbe unacceptably decreased. If the joining is weak, the light source unit23 can become detached from the slider 22 during a subsequent processstep such as a cleaning step, or during use of the head.

FIGS. 7 a 1 to 7 j show schematic views illustrating one embodiment ofthe method for manufacturing the thermally-assisted magnetic recordinghead 21 in which a light source unit 23 is joined to a slider 22according to the present invention. For clarity, a solder layer 58provided on the slider back surface 2201 of the slider 22 is omittedfrom FIGS. 7 a 1 to 7 h and FIG. 7 j.

Referring to FIGS. 7 a 1 and 7 a 2, first the light source unit 23 isheld with a back holding jig 62 having at least one suction hole 630which reaches a suction surface 620 of the back holding jig 62.Specifically, the unit back surface 2303 of the light source unit 23 isadhered to the suction surface 620 of the back holding jig 62 bysuction. The adhesion of the light source unit 23 by suction by thesuction hole 630 is accomplished by activating an evacuator 63 connectedto one end of the suction hole 630 to decrease the air pressure in thesuction hole 630. Here, the force sucking the light source unit 23depends on the inner diameter of the suction hole 630, the number ofsuction holes 630 provided, and the degree of evacuation by theevacuator 63, and can be adjusted in a considerable range. In thepresent embodiment, the suction force is adjusted to have a magnitudesuch that the position or orientation of the light source unit 23 ischanged under a predetermined load applied. The adjustment enableseffective adjustment of the conformity of the joining surface 2300 withthe round-tipped rod 65 in a subsequent step.

The light source unit 23 is adhered in a position such that its joiningsurface 2300 is positioned below (on −X side of) the lower surface 621of the back holding jig 62. This positioning allows the light sourceunit 23 to come into contact with the slider 22 while preventing theback holding jig 62 from contacting the slider 22 when the back holdingjig 62 is brought close to the slider 22. Here, the joining surface 2300does not need to be brought into parallelism with the lower surface 621when the light source unit 23 is sucked. This is because the conformityof the joining surface 2300 will be adjusted by application of a load bythe round-tipped rod 65 in a subsequent step. Consequently, the step ofholding the light source unit 23 with the back holding jig 62 can berelatively readily completed in a short time.

Then the back holding jig 62 is moved close to the slider 22 to bringthe light source unit 23 adhered to the back holding jig 62 by suctionclose to or into contact with the slider back surface 2201 of the slider22 as illustrated in FIG. 7 b. The back holding jig 62 is then broughtcloser to the slider 22 until the distance between the lower surface 621of the back holding jig 62 and the slider back surface 2201 reaches apredetermined value, for example several tens of μm, thereby pressingthe light source unit 23 against the slider 22 as illustrated in FIG. 7c. The pressing does not necessarily provide an adequate conformity ofthe joining surface 2300 of the light source unit 23 to the slider backsurface 2201. One surface of a component in general does not necessarilyreadily conform to a reference surface simply by pressing the surfaceagainst the reference surface.

Then the round-tipped rod 65 is pressed against the load applicationsurface 2301 of the light source unit 23 to apply a load to the lightsource unit 23 as illustrated in FIG. 7 d. This load enables the joiningsurface 2300 of the light source unit 23 to conform to the slider backsurface 2201 of the slider 22 at least in the track width direction (inY-axis direction). At this stage, the joining surface 2300 conforms tothe slider back surface 2201 in the direction along the track (in Z-axisdirection) as well in the present embodiment. The area of contact of theround-tipped rod 65 with the load application surface 2301 issignificantly smaller than the area of the joining surface 2300. Sincethe light source unit 23 is pressed by such a small contact area, thejoining surface 2300 adequately conforms to the slider back surface 2201in the process of being pressed against the slider back surface 2201even if the joining surface 2300 is tilted at a small angle to theslider back surface 2201.

Here, the round-tipped rod 65 is connected to a loading unit 660 througha load cell 661 (FIG. 4) which is a weight sensor. This arrangementenables the magnitude of the load applied to the light source unit 23 tobe adjusted to a proper value, for example a value in the range of 10 to200 gf (grams-force), for achieving conformity. The suction force of thesuction hole 630 with which the light source unit 23 is sucked has beenadjusted so that the light source unit 23 is moved by a predeterminedload applied to the light source unit 23 as has been describedpreviously. Consequently, even though the back holding jig 62 standsstill, the light source unit 23 can be moved by the pressure from theround-tipped rod 65 so that the joining surface 2300 can conform to theslider back surface 2201.

Then, as illustrated in FIG. 7 e, the probes 67 are placed in contactwith a lead electrode 411 provided on the source-installation surface2302 of the light source unit 23 and an n-electrode 40 which forms theupper surface of the laser diode 40. Since the light source unit 23 isheld at the back by the standing-still back holding jig 62, the lightsource unit 23 is not moved by the pressure from the probes 67 and thejoining surface 2300 remains conformed to the slider back surface 2201.When the probes 67 are applied, the round-tipped rod 65 is preferablyheld pressed against the light source unit 23 to further ensure that thelight source unit 23 is prevented from moving.

As illustrated in FIG. 7 f, the round-tipped rod 65 is then raised torelease the load from the light source unit 23 and the back holding jig62 is moved away from the slider 22 to position the light source unit 23at a predetermined distance D_(US), for example several μm, from theslider 22. At this distance, the conformity of the joining surface 2300of the light source unit 23 to the slider back surface 2201 in the trackwidth direction (in Y-axis direction) is maintained high whereas theconformity in the direction along the track (in Z-axis direction) islow. This is because the light source unit 23 moves in the direction inwhich the light source unit 23 adheres again to the suction surface 620of the back holding jig 62. The probes 67 follow the movement of thelight source unit 23 and remain pressed against the lead electrode 411and the n-electrode 40 a.

While the joining surface 2300 is in that conforming state, thelight-emitting center 4000 of the laser diode 40 in the light sourceunit 23 is aligned with the light-receiving end surface 430 of theoptical system 31 in the slider 22 in directions in the plane of theslider back surface 2201 (directions in YZ-plane) by active alignment asillustrated in FIG. 7 g. Specifically, electric power is supplied to thelaser diode 40 through the probes 67 to actually put the laser diode 40in operation while the light source unit 23 (laser diode 40) is beingmoved with respect to the slider 22 (optical system 31). Then, while thelight source unit 23 is being moved, laser light 72 emitted from thelight-emitting center 4000 of the laser diode 40 and incident on thelight-receiving end surface 430 of the optical system 31 is monitored onthe light-emitting end side of the optical system 31 (on the end surface36 a side of the NF-light generator 36) in real time until the lightintensity in the monitoring location is maximized, then the maximumintensity position is set as the desired relative position of the lightsource unit 23 (laser diode 40) with respect to the slider 22 (opticalsystem 31). According to the active alignment, a desired light path canbe actually reliably provided after joining and an extremely highaccuracy in position of the junction between the light source unit 23and the slider 22 can be achieved.

Laser light 72 emitted from the head end surface 2210 of the slider 22or converted NF-light can be monitored in real time with a photodetector73 such as a photodiode provided on the head end surface 2210 side ofthe slider 22. The photodetector 73 is connected to the controller 69and the movement of the back holding jig 62 (light source unit 23) inYZ-plane can be controlled on the basis of a monitor output from thephotodetector 73.

During the alignment described above, the laser diode 40 keeps operatingand radiating considerable heat. However, by making the back holding jig62 of a metal that has a high thermal conductivity, such as stainlesssteel or Cu (copper) and using the back holding jig 62 also as aheatsink, considerable heat radiated from the laser diode 40 can bedissipated through the unit substrate 230. Consequently, oscillation ofthe laser diode 40 is stabilized and the good active alignment can beachieved.

After completion of the alignment of the light source unit 23 and theslider 22, the back holding jig 62 is moved in −X direction closer tothe slider 22 to move the light source unit 23 back toward the slider 22by the distance D_(US) over which the light source unit 23 has beenmoved in the step in FIG. 7 f, thereby bringing the light source unit 23into contact with the slider 22 as illustrated in FIG. 7 h. Theoperation does not change the relative position of the light source unit23 with respect to the slider 22 in YZ-plane. Then the round-tipped rod65 is pressed against the load application surface 2301 of the lightsource unit 23 to apply a load to the light source unit 23 again. Theload may be in the range of 10 to 200 gf (grams force), for example. Theapplication of the load enables the joining surface 2300 of the lightsource unit 23 to conform to the slider back surface 2201 of the slider22 both in the track width direction (Y-axis direction) and thedirection along the track (Z-axis direction).

Then as illustrated in FIG. 7 i, a solder layer 58 provided on theslider back surface 2201 of the slider 22 is melted to join the lightsource unit 23 to the slider 22. Here, the light source unit 23 and theslider 22 have been aligned with each other in YZ-plane and then movedalong X-axis direction to be attached to each other with the solderlayer 58 between them. In the present embodiment, the solder layer 58 isirradiated, through the unit substrate 230, with light 74 that has apredetermined wavelength that passes through the unit substrate 230. Thesolder layer 58 is melted by the irradiation with the light 74 and thensolidified to join the light source unit 23 to the slider 22. The placewhere the solder layer 58 is formed previously is not limited to theslider back surface 2201; the solder layer 58 may be formed previouslyon the joining surface 2300 of the light source unit 23 or on both ofthe slider back surface 2201 and the joining surface 2300.

The light 74 may be Nd-YAG laser light (with a wavelength of 1064 nm)emitted from an Nd-YAG laser oscillator 76, which is a light source foradhesion, through an optical fiber 75. Here, YAG is the name of acrystal having a garnet structure, made of a composite oxide (Y₃Al₅O₁₂)of Y (yttrium) and Al (aluminum). Nd-YAG laser light can be obtained byusing a YAG crystal in which several percent of Y is replaced with Nd(neodymium) as the laser medium and is widely used in research,industrial, medical and other applications. If Nd-YAG laser light isused as the light 74, the unit substrate 230 is made of a material thathas a transmittance higher than or equal to 50% at a wavelength of 1064nm, such as Si (with a transmittance of 67%), GaAs (with a transmittanceof 66%), or SiC (with a transmittance of 80%), so that the solder layer58 can be irradiated with a sufficient amount of light 74 for meltingthrough the unit substrate 230. The light 74 may be other type of laserlight such as YAG laser light other than Nd-YAG laser light, solid-statelaser light other than YAG laser light, or gas laser light such ascarbon dioxide gas laser light. It is essential that light having awavelength capable of passing through the unit substrate 230 and havingoutput power required for melting the solder layer 58 is used or a unitsubstrate 230 made of a material capable of passing the wavelength ofthe light used is used. Preferably, the position and suction operationof the back holding jig 62 are maintained and the application of loadwith the round-tipped rod 65 is also continued during the step of thejoining under irradiation with light 74.

The solder layer 58 is preferably made of an alloy having a meltingpoint lower than 400° C. For example, if the solder layer 58 is made ofan Au—Sn alloy (containing 20 wt. % of Sn), the melting point of thesolder layer 58 will be approximately 280° C. Experiments have shownthat irradiation of the solder layer 58 with Nd-YAG laser light 74having light output power of 0.1 kW, a spot diameter of 100 μm, and apulse width of 4 microseconds, for example, through the light sourceunit 23 melts the solder layer 58 sufficiently well enough to bond thelight source unit 23 to the slider 22.

The adhesion of the light source unit 23 to the slider 22 with thesolder layer 58 under irradiation with light 74 in this way completesthe joining of the light source unit 23 to the slider 22. Thus, athermally-assisted magnetic recording head 21 has been fabricated. Inthe head 21, the light source unit 23 and the slider 22 are joinedtogether with the solder layer 58 between them. Consequently, a heatdissipation path through which heat radiated from the laser diode 40 inlight-emitting operation is transferred sequentially to the unitsubstrate 230, to the solder layer 58, to the slider substrate 220 andto a magnetic recording medium, can be provided during write operationsby the head 21 flying above the magnetic recording medium. Thefabricated thermally-assisted magnetic recording head 21 can betransferred together with the back holding jig 62 to a working locationwhere the next process step, for example a cleaning step, is performed,with the adhesion of the light source unit 23 to the back holding jig 62by suction being maintained as illustrated in FIG. 7 j.

According to the method for manufacturing the thermally-assistedmagnetic recording head 21 according to the present invention describedwith reference to FIGS. 7 a 1 to 7 j, the “conformity” between thejoining surface 2300 of the light source unit 23 and the slider backsurface 2201 of the slider 22 can be significantly increased while thelight source unit 23 and the slider 22 can be aligned with each other byactive alignment. Accordingly, an adequately strong junction and anadequately high accuracy of the joining position can be achieved in thejoining between the light source unit and the slider. Furthermore, sincethe heat dissipation path for dissipating heat from the laser diode 40after the joining can be provided, stable oscillation of the laser diode40 can be provided and consequently a good thermal assist effect can beachieved.

FIG. 8 shows a perspective view schematically illustrating a structureof a major part in one embodiment of a magnetic recording apparatusaccording to the present invention. FIG. 9 shows a perspective viewschematically illustrating a structure of a major part in one embodimentof an HGA according to the present invention. In FIG. 9, the side of theHGA opposed to the surface of the magnetic disk is presented as theupper side.

A magnetic disk apparatus as a magnetic recording apparatus shown inFIG. 8 includes: a plurality of magnetic disks 10 rotating around arotational axis of a spindle motor 11; an assembly carriage device 12provided with a plurality of drive arms 14 thereon; an HGA 17 attachedon the top end portion of each drive arm 14 and provided with athermally-assisted magnetic recording head 21; and arecording/reproducing and light-emission control circuit 13 forcontrolling write/read operations of the thermally-assisted magneticrecording head 21 and further for controlling the emission operation ofa laser diode 40 as a light source that generates laser light forthermally-assisted magnetic recording.

The magnetic disk 10 is, in the present embodiment, designed forperpendicular magnetic recording, and has a structure in which, forexample, sequentially stacked on a disk substrate is: a soft-magneticunder layer; an intermediate layer; and a magnetic recording layer(perpendicular magnetization layer). The assembly carriage device 12 isa device for positioning the thermally-assisted magnetic recording head21 above a track formed on the magnetic recording layer of the magneticdisk 10, on which recording bits are aligned. In the apparatus, thedrive arms 14 are stacked in a direction along a pivot bearing axis 16and can be angularly swung around the axis 16 by a voice coil motor(VCM) 15. The structure of the magnetic disk apparatus according to thepresent invention is not limited to that described above. For instance,the number of each of magnetic disks 10, drive arms 14, HGAs 17 andsliders 21 may be one.

Referring to FIG. 9, a suspension 20 in the HGA 17 includes a load beam200, a flexure 201 with elasticity fixed to the load beam 200, a baseplate 202 provided on the base portion of the load beam 200, and awiring member 203 provided on the flexure 201 and made up of leadconductors and connection pads electrically joined to both ends of thelead conductors. The thermally-assisted magnetic recording head 21 isfixed to the flexure 201 at the top end portion of the suspension 20 soas to face the surface of each magnetic disk 10 with a predeterminedspace (flying height). Here, an aperture 2010 is provided in the flexure201; the thermally-assisted magnetic recording head 21 is fixed in sucha way that the light source unit 23 protrudes from the opposite side ofthe flexure 201 through the aperture 2010.

Moreover, connection pads that form one end of the wiring member 203 areelectrically connected to terminal electrodes 370 and 371 (FIG. 1) forthe magnetic head element 32 of the thermally-assisted magneticrecording head 21, and further to the lead electrode 411 of the lightsource unit 23 and the n-electrode 40 a (FIG. 1) of the laser diode 40by wire bonding, SBB or the like. These connections enable the MRelement 33, the electromagnetic transducer and the laser diode 40 toreceive electric power and to be brought into operation. The structureof the suspension 20 is not limited to the above-described one. An ICchip for driving the head may be mounted midway on the suspension 20,though not shown.

All the foregoing embodiments are by way of example of the presentinvention only and not intended to be limiting, and many widelydifferent alternations and modifications of the present invention may beconstructed without departing from the spirit and scope of the presentinvention. Accordingly, the present invention is limited only as definedin the following claims and equivalents thereto.

1. A method for manufacturing a thermally-assisted magnetic recordinghead in which a light source unit including a light source provided in aunit substrate and a slider including an optical system provided in aslider substrate are joined to each other, the manufacturing methodcomprising the steps of: adhering by suction a unit back surface of theunit substrate with a back holding jig including a suction means, theunit back surface being opposite to a source-installation surface of theunit substrate; moving the back holding jig close to the slider to bringthe light source unit adhered to the back holding jig by suction intocontact with a slider back surface of the slider, the slider backsurface being opposite to an opposed-to-medium surface of the slider andincluding a light-receiving end surface of the optical system; applyinga load to a load application surface of the unit substrate by a loadingmeans to bring a joining surface of the light source unit intoconformity with the slider back surface of the slider at least in atrack width direction, the load application surface being opposite tothe joining surface that is to be joined to the slider; stoppingapplying the load, moving the back holding jig away from the slider toposition the light source unit at a distance from the slider, and thenaligning a light-emitting center of the light source with thelight-receiving end surface of the optical system in directions in aplane of the slider back surface; moving the back holding jig againclose to the slider to bring the light source unit into contact with theslider back surface of the slider; and applying a load again to the loadapplication surface of the unit substrate by the loading means to bringthe joining surface of the light source unit into conformity with theslider back surface of the slider.
 2. The manufacturing method asclaimed in claim 1, wherein probes are brought into contact withelectrodes for the light source provided in the light source unit,electric power is supplied to the light source to put the light sourcein emitting operation, and then the light-emitting center of the lightsource is aligned with the light-receiving end surface of the opticalsystem so that a light from the light source enters the optical system.3. The manufacturing method as claimed in claim 1, wherein a suctionforce of the suction means provided in the back holding jig, with whichthe light source unit is sucked, has a magnitude such that a position ororientation of the light source unit is changed under a predeterminedload applied.
 4. The manufacturing method as claimed in claim 1, whereinthe suction means included in the back holding jig is at least onesuction hole provided in the back holding jig, and the light source unitis adhered by suction to the back holding jig by activating an evacuatorconnected to one end of the at least one suction hole.
 5. Themanufacturing method as claimed in claim 1, wherein the loading means isa jig having a spherical or convex portion which is to contact with theload application surface of the unit substrate.
 6. The manufacturingmethod as claimed in claim 1, further comprising the steps of: formingan adhesion material layer previously on the joining surface of thelight source unit or the slider back surface of the slider or on both ofthe surfaces, and bringing the joining surface into conformity with theslider back surface with the adhesion material layer sandwichedtherebetween; irradiating the adhesion material layer with a light thatincludes a wavelength that passes through the unit substrate through theunit substrate to melt the adhesion material layer; and bonding thelight source unit and the slider.
 7. A joining apparatus configured tojoin a light source unit and a slider, the joining apparatus comprising:a fixture for supporting the slider; a back holding jig comprising: asuction means for adhering the light source unit by suction; and asuction surface that is to contact with a unit back surface of a unitsubstrate, the back holding jig being capable of moving to adjustrelative position of the light source unit with respect to the sliderheld in the fixture; a loading means for applying a load to a loadapplication surface of the unit substrate; probes to be pressed againstelectrodes for a light source provided in the light source unit,provided for supplying electric power to the light source in order toalign a light-emitting center of a light source with a light-receivingend surface of an optical system in directions in a plane of a sliderback surface; and a controller configured to control movement of theback holding jig, suction by the suction means, application of load bythe loading means, movement of the probes, and power supply to the lightsource through the probes, as appropriate.
 8. The joining apparatus asclaimed in claim 7, further comprising a photodetector for detecting alight that is emitted from the light source to which electric power isapplied through the probes, propagated through the optical system, andemitted from an opposed-to-medium surface of the slider when aligningthe light-emitting center of the light source with the light-receivingend surface of the optical system.
 9. The joining apparatus as claimedin claim 7, wherein the suction means included in the back holding jigis at least one suction hole provided in the back holding jig, and oneend of the at least one suction hole reaches the suction surface and theother end is connected to an evacuator.
 10. The joining apparatus asclaimed in claim 7, wherein the loading means is a jig having aspherical or convex portion which is to contact with the loadapplication surface of the unit substrate.
 11. The joining apparatus asclaimed in claim 7, further comprising an adhesion light source foradhesion for irradiating an adhesion material layer with a light thatincludes a wavelength that passes through the unit substrate through theunit substrate, in order to melt the adhesion material layer and thus tobond the light source unit and the slider after forming the adhesionmaterial layer previously on the joining surface of the light sourceunit or the slider back surface of the slider or on both of the surfacesand bringing the joining surface into conformity with the slider backsurface with the adhesion material layer sandwiched therebetween.